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Signed on the foot: 'J.ZENTMAYER PHILA, PAT. AUG 15 76'

Serial Number:None


Zentmayer American Columbian Microscope


This microscope has several unique features. It arises on a Y-staped foot with a hollow conical support which provides a uniquely stable support in both vertical and inclined and even horizontal positions but with less weight than many other equally stable designs. It is signed as noted above, without a serial number. It is engraved on the front of the main optical tube Prize 1897, B Kohn. The stage is a standard Zentmayer gliding stage, but with a permanent stage forceps attached to one of the handles. This well-made addition includes an alligator clip frequently used in electical work and has the labelling of Mueller Elec. Co. Cleveland O. U.S.A. There were three objectives on a triple nosepiece. These include:

  1. Bausch & Lomb Optical, Rochester N.Y. 2/3 tube length 160 (engraved in OLD ENGLISH)
  2. SPENCER LENS CO. 67286, HOMOG. IMMER. 1.8 MM N.A. 1.30 95X
  3. An objective marked only with a tiny hand-scratched capital L on the blackened end.


Coarse focus is by straight rack and pinion, fine is the patented Zentmayer long lever. The Zentmayer swinging tailpiece allows the substage to slide up or down on it, and the mirror has up or down movement via its support which rides inside the tailpiece.

Zentmayer Columbian Microscope

Zentmayer Columbian Microscope

Zentmayer Columbian Microscope Stage forceps

Zentmayer Columbian Microscope

Zentmayer Columbian Microscope

Zentmayer Columbian Microscope Stage


Joseph Zentmayer is one of the great names in microscopes not only in America, but worldwide. His inventions included his improvement in the swinging substage which has its axis of rotation centered at the stage, the gliding stage(found on his Grand American Microscope, a unique form of variable diameter diaphragm, and a long lever type of fine adjustment. He was also the first to make a centerable substage that could be centered for high powered objectives. This is found on his 'Grand American' where the adjustments are made by slotted screws. Bulloch later changed the plan from screws to milled knobs. Zentmayer's swinging substage design was incorporated into the microscopes of many other makers of his day including Ross who termed them the Ross-Zentmayer Model. The Zentmayer swinging substage became standard equipment on microscopes by nearly all the major manufacturers of the day. It led to even more extreme concoctions to achieve even more oblique illumination. The unique form of the American Histological, first patented in 1876, was very popular and later led to this (American columbian) stand starting about 1893. This certainly correlates with the engraved 1897 date. Changes in the Columbian as compared to the American Histological, are relatively minor, at least externally; the upright cone is a bit higher, the mirror can be adjusted to be closer or further from the stage, and the stage is slightly different in size.

The purpose of the prize for B. Kohn remains a mystery at least for the moment as neither a reference to this prize or B. Kohn has yet been found. Of course I would welcome any additional information.